U.S. patent number 5,887,554 [Application Number 08/589,118] was granted by the patent office on 1999-03-30 for rapid response plasma fuel converter systems.
Invention is credited to Daniel R. Cohn, Alexander Rabinovich, Charles H. Titus.
United States Patent |
5,887,554 |
Cohn , et al. |
March 30, 1999 |
Rapid response plasma fuel converter systems
Abstract
Systems for producing hydrogen-rich gases including rapid
response plasma fuel converters are provided. The rapid response
plasma fuel converters systems are suitable for use in vehicles and
the like in which the systems are capable of instantaneously
providing hydrogen-rich gas, reducing pollutants during vehicle
startup and allowing use of hydrogen-rich gas during load changes.
The systems are preferably capable of responding on the order of a
second or less. The systems include a plasma fuel converter for
receiving hydrocarbon fuel and reforming the hydrocarbon fuel into
a hydrogen-rich gas, an internal combustion engine adapted to
receive the hydrogen-rich gas from the plasma fuel converter, a
generator powered by the engine and connected to deliver electrical
energy to power the plasma fuel converter, and a power supply
circuit capable of rapidly providing power to the plasma fuel
converter in response to a stimulus. The stimulus can be movement
in the accelerator pedal controlled by the driver of the vehicle.
The plasma fuel converters can be operated pulsed or non-pulsed
modes of operation and can utilize arc or high frequency
discharges. The plasma fuel converter can be either separated from
the engine or directly integrated into the engine to allow for more
efficient use of the thermal energy produced by the plasma fuel
converter.
Inventors: |
Cohn; Daniel R. (Chestnuthill,
MA), Rabinovich; Alexander (Salem, MA), Titus; Charles
H. (Newtown Sq., PA) |
Family
ID: |
24356672 |
Appl.
No.: |
08/589,118 |
Filed: |
January 19, 1996 |
Current U.S.
Class: |
123/3;
123/DIG.12 |
Current CPC
Class: |
F02M
25/12 (20130101); F02B 51/00 (20130101); F02B
43/10 (20130101); F02B 2043/106 (20130101); Y02T
10/12 (20130101); Y10S 123/12 (20130101); Y02T
10/30 (20130101) |
Current International
Class: |
F02B
43/10 (20060101); F02B 25/00 (20060101); F02B
25/12 (20060101); F02B 43/00 (20060101); F02B
51/00 (20060101); F02B 043/10 () |
Field of
Search: |
;123/3,DIG.12 |
References Cited
[Referenced By]
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2 620 436 |
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30 48 540 A1 |
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2 241 746 |
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Sep 1991 |
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GB |
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WO 85/00159 |
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WO |
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|
Primary Examiner: Solis; Erick R.
Attorney, Agent or Firm: Choate, Hall & Stewart
Claims
What is claimed is:
1. A power system comprising:
a plasma fuel converter for receiving hydrocarbon fuel and
reforming the hydrocarbon fuel into a hydrogen-rich gas;
an internal combustion engine adapted to receive the hydrogen-rich
gas from the plasma fuel converter, the engine operating at a load
condition;
a generator powered by the engine and connected to deliver
electrical energy to power the plasma fuel converter; and
a power supply circuit configured to provide power with a
controlled voltage/current ratio to the plasma fuel converter in
response to a change in the load condition.
2. The power system of claim 1, wherein the system is configured to
respond in about one second or less.
3. The power system of claim 1, wherein the plasma fuel converter
utilizes an arc discharge or a high frequency discharge.
4. The power system of claim 3, wherein the high frequency
discharge is provided by inductive or microwave heating.
5. The power system of claim 1, wherein the plasma fuel converter
is an arc plasmatron.
6. The power system of claim 5, wherein the power supply circuit
comprises:
a transformer connected to the generator;
a battery electrically connected to the generator; and
an ignition system electrically connected to the battery and
configured to initiate discharges in the plasmatron.
7. The power system of claim 6, further including a plurality of
saturable toroidal reactors connected to the transformer and
configured to control current.
8. The power system of claim 7, further including a rectifier
electrically connected to plurality of saturable toroidal reactors
and to the plasmatron.
9. The power system of claim 8, wherein the generator is configured
to deliver three-phase AC current to the transformer and the
rectifier is configured to supply DC current to the plasmatron.
10. The power system of claim 6, further including a controller and
a fuel injector configured to maintain a predetermined mixture of
the hydrocarbon fuel and the air introduced into the plasmatron in
response to the change in the load condition.
11. The power system of claim 1, further including a controller and
a fuel injector configured to maintain a predetermined mixture of
the hydrocarbon fuel and the air introduced into the plasmatron in
response to the change in the load condition.
12. The power system of claim 1, wherein the system is used in a
vehicle and the change in the load condition is movement in an
accelerator pedal in the vehicle.
13. The power system of claim 1, wherein the plasma fuel converter
is a partial oxidation plasmatron.
14. The power system of claim 13, further including a controller
and a fuel injector configured to maintain a predetermined mixture
of the hydrocarbon fuel and the air introduced into the plasmatron
in response to the change in the load condition.
15. The power system of claim 14, wherein the predetermined mixture
of the hydrocarbon fuel and the air introduced into the plasmatron
is about equal to a stoichiometric ratio of fuel to air.
16. The power system of claim 13, wherein the system is configured
for a pulsed mode of operation.
17. The power system of claim 13, wherein the system is configured
for pulsed and non-pulsed modes of operation.
18. The power system of claim 13, wherein the plasmatron is a
pulsed railgun plasmatron.
19. The power system of claim 13, wherein the plasmatron is a
pulsed gliding discharge fuel plasmatron.
20. The power system of claim 1, wherein the plasma fuel converter
is a pulsed pinch plasmatron with gliding radial discharge.
21. The power system of claim 1 wherein the plasma fuel converter
is integrated with the internal combustion engine.
22. The power system of claim 21, wherein the plasma fuel converter
is a pulsed gliding discharge fuel plasmatron.
23. The power system of claim 22, further including a heat
exchanger configured to preheat incoming air to the plasmatron.
24. The power system of claim 21, wherein the power supply circuit
comprises:
a transformer connected to the generator;
a battery electrically connected to the generator; and
an ignition system electrically connected to the battery and
configured to initiate discharges in the plasma fuel converter.
25. The power system of claim 21, further including a first
carburetor for controllably introducing a fuel and air into the
combustion chamber of the internal combustion engine.
26. The power system of claim 25, further including a second
carburetor for controllably introducing the hydrocarbon fuel and
air into the plasma fuel converter.
27. The power system of claim 26, further including a fast action
valve positioned between the second carburetor and the plasma fuel
converter.
28. The power system of claim 21, wherein the plasma fuel converter
is integrated with the internal combustion engine such that thermal
energy in the hydrogen-rich gas can be used in the internal
combustion engine.
29. The power system of claim 28, further including at least one
heat exchanger configured to preheat incoming air to the plasma
fuel converter.
30. The power system of claim 21, further including a heat
exchanger configured to preheat incoming air to the plasma fuel
converter.
31. The power system of claim 21, further including a catalytic or
thermal fuel reformer connected to the plasma fuel converter and
the internal combustion engine.
Description
TECHNICAL FIELD
The present invention generally relates to systems including rapid
response plasma fuel converters for supplying hydrogen-rich gas to
internal combustion engines. The invention more particularly
relates to systems including rapid response plasmatrons suitable
for use in vehicles and the like in which the systems are capable
of instantaneously providing hydrogen-rich gas, reducing pollutants
during vehicle startup and allowing use of hydrogen-rich gas during
load changes.
BACKGROUND OF THE INVENTION
Hydrogen is attractive as a fuel or additive for internal
combustion engines because hydrogen as a fuel source can
significantly reduce air pollution and can also serve as an
alternative energy source to gasoline. See Mishchenko, et al.,
Proc. VII World Hydrogen Energy Conference, Vol. 3 (1988), Belogub,
et al., Int. J. Hydrogen Energy, Vol. 16, 423 (1991), Varde, et
al., Hydrogen Energy Progress V, Vol. 4 (1984), Feucht, et al.,
Int. J. Hydrogen Energy, Vol 13, 243 (1988), Chuveliov, et al., In:
Hydrogen Energy and Power Generation, T. Nejat Veziroglu, Ed., Nova
Science Publisher, New York, N.Y. (1991), Das, Int. J. Hydrogen
Energy, Vol 16, 765 (1991). Moreover, engine efficiency can be
10-50% higher when running on hydrogen as compared with a gasoline
engine. Prior art systems contemplated either storing hydrogen
on-board or generating it on board. On-board storage requires high
pressure vessels, cryogenic containers if the hydrogen is to be
stored as a compressed gas or liquid, or large getter volumes and
weights if the hydrogen is to be stored as a hydride. Moreover, the
refill time for hydrogen is substantially longer than that for
gasoline when the hydrogen is to be stored on-board.
As to the on-board production of hydrogen, several approaches have
been disclosed in the prior art. For example, U.S. Pat. No.
5,143,025 to Munday discloses the use of electrolysis to separate
water into hydrogen and oxygen and introducing the hydrogen into an
internal combustion engine. In U.S. Pat. No. 5,159,900 to Dammann,
hydrogen gas is produced by water interaction with solid carbon.
Electrical current is passed between the carbon electrodes causing
the electrodes to burn and oxidize to form carbon monoxide and
hydrogen. U.S. Pat. No. 5,207,185 to Greiner et al. discloses a
burner which utilizes a portion of the hydrocarbon fuel to reform
another portion to produce hydrogen. The hydrogen is then mixed
with the hydrocarbon fuel for introduction into an internal
combustion engine.
Another system diverts a fraction of the gasoline from the flow
path to the engine and is passed through a thermal converter and
steam reformed to yield hydrogen-rich gas. See, Breshears, et al.,
Proc. of EPA 1st Symposium on Low Pollution Power Systems
Development, 268 (1973). We note that the authors state that this
system would not be practical to generate hydrogen as the sole fuel
for an engine. Yet another system of this type uses partial
oxidation in a catalytic converter to produce hydrogen rich gas.
See Houseman, et al., Proc. 3rd World Hydrogen Energy Conf., 949
(1980). This system requires carefully controlled catalytic action
and temperature range and has limitations for startup and transient
response.
U.S. Pat. Nos. 5,425,332 and 5,437,250, both to Rabinovich et al.,
disclose plasmatron-internal combustion engine systems. The systems
disclosed include a source of hydrocarbon fuel which is supplied to
a plasmatron which reforms the fuel into a hydrogen-rich gas.
Plasmatrons heat an electrically conducting gas either by an arc
discharge or by a high frequency inductive or microwave discharge.
An internal combustion engine is connected to receive the
hydrogen-rich gas from the plasmatron. While these systems are
significant improvements over the prior art, it would be desirable
to provide systems that are capable of rapid response for
instantaneously providing hydrogen-rich gas, reducing pollutants
during startup and allowing use of hydrogen-rich gas during typical
load changes. The entire contents of both U.S. Pat. Nos. 5,425,332
and 5,437,250 are incorporated herein by reference.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide systems for
producing hydrogen-rich gas that utilize plasma fuel converters
capable of rapid response.
It is another object of the invention to provide rapid response
systems capable of generating hydrogen-rich gas on the order of a
second or less.
It is another object of the invention to provide systems for
generating hydrogen-rich gas that reduce vehicle emission
pollutants during startup or regular operation.
It is a further object of the invention to provide systems for
generating and utilizing hydrogen-rich gas during load changes.
It is another object of the invention to provide systems for
generating hydrogen-rich gas in which the power for processing the
fuel source in the plasma fuel converter can be rapidly varied
according to the flow rate to satisfy engine load requirements.
It is yet another object of the invention to provide rapid response
systems for generating hydrogen-rich gas in which the power for
processing the fuel in a continuous arc plasmatron is varied by
optimal variation of both arc plasma voltage and current.
It is a further object of the invention to provide rapid response
systems for producing hydrogen-rich gas which include a plasmatron
capable of pulsed or non-pulsed modes of operation.
It is a further object of the invention to integrate the plasma
fuel converter with the engine in order to make more efficient use
of the thermal energy of the plasma fuel converter produced
hydrogen-rich gas.
These and other objects of the invention are provided by rapid
response systems that include a plasma fuel converter for receiving
hydrocarbon fuel and reforming the hydrocarbon fuel into a
hydrogen-rich gas, an internal combustion engine connected to
receive the hydrogen-rich gas from the plasma fuel converter, a
generator powered by the internal combustion engine and connected
to deliver electrical energy to power the plasma fuel converter,
and a power supply circuit capable of rapidly providing power to
the plasma fuel converter in response to a stimulus. The systems
provided by the present invention can be implemented in vehicles
such that the stimulus controlling the power supply circuit is a
change in the accelerator pedal of the vehicle, which is controlled
by the driver of the vehicle. Master control systems and fast
action valves can be utilized to control the introduction of air
and fuel into the plasma fuel converter.
The power supply circuit includes a transformer connected to the
generator, a battery connected to the generator, and an ignition
system electrically connected to the battery and capable of
initiating arc discharges in the plasma fuel converter and
delivering power to the internal combustion engine. The transformer
preferably includes a plurality of saturable toroidal reactors
capable of controlling current electrically connected thereto and
the generator preferably delivers three-phase AC current to the
transformer. A rectifier is connected to the plasma fuel converter
and to the transformer such that DC current is supplied to the
plasma fuel converter. The systems also preferably include an
ignition system and pulse network (PN).
The foregoing has outlined some of the more pertinent objects of
the present invention. These objects should be construed to be
merely illustrative of some of the more prominent features and
applications of the invention. Many other beneficial results can be
attained by applying the disclosed invention in a different manner
of modifying the invention as will be described. Accordingly, other
objects and a fuller understanding of the invention may be had by
referring to the following Detailed Description of the Preferred
Embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the present invention, reference is
had to the following description taken in conjunction with the
accompanying drawings, in which:
FIG. 1 is a block diagram illustrating a system for fuel and air
control for a rapid response plasma fuel converter in accordance
with the present invention;
FIG. 2 illustrates a power control circuit for a continuous arc
plasma fuel converter according to the invention;
FIG. 3 is a block diagram showing a pulsed plasmatron-engine
electrical system;
FIG. 4 is a cross-sectional view of a pulsed railgun plasma fuel
converter;
FIG. 5 is a cross-sectional view of a pulsed gliding discharge fuel
converter;
FIG. 6 is a cross-sectional view of a pulsed pinch plasmatron with
gliding radial discharge;
FIG. 7 is a cross-sectional view of a pulsed gliding discharge for
an integrated plasmatron hydrogen-rich gas generation-engine system
according to an embodiment of the present invention;
FIG. 8 is a cross-sectional view of a pulsed plasmatron-cylinder
system for the production of hydrogen-rich gas and electricity;
and
FIG. 9 is a block diagram illustrating a hybrid plasma fuel
converter-catalytic partial oxidation reformer for use in the
present invention.
Similar reference characters refer to similar parts throughout the
several views of the drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As discussed in U.S. Pat. Nos. 5,425,332 and 5,437,250, plasma
devices can provide an effective means for onboard conversion of
gasoline and other fuels into hydrogen-rich gas (hydrogen and
carbon monoxide) for use in vehicular internal combustion engines
and for other applications. Use of hydrogen-rich gas in mixtures
with gasoline produces a faster flame front which makes it possible
to greatly reduce the amount of fuel in the cylinder charge. In
such lean operation the charge temperature is significantly
reduced, thereby greatly decreasing the production of nitrogen
oxides (NO.sub.x). Carbon monoxide and hydrocarbon emissions can
also be significantly reduced. In addition to gasoline, other fuel
sources for conversion into hydrogen-rich gas include: diesel, oil,
heating oil, methanol, ethanol, and natural gas. In order to
further reduce pollutants, it is desirable to provide a plasmatron
that is capable of rapid response such that hydrogen-rich gas can
be instantaneously provided, pollutants during vehicle startup can
be reduced and hydrogen-rich gas can be used during load
changes.
In one embodiment of the invention, the plasmatron is used in a
partial oxidation reforming mode rather than as a steam reformer
plasmatron. In the partial oxidation mode, the plasmatron is
employed to provide the optimal temperature for a rich mixture of
hydrocarbon fuel and air. While steam reforming could be a useful
option for some applications, partial oxidation reformation
minimizes electrical power requirements and can greatly reduce or
eliminate the need for water (in contrast to steam reforming). The
partial oxidation reaction between hydrocarbon fuel and air is
exothermic and produces hydrogen, carbon monoxide and nitrogen. The
reaction in a partial oxidation plasmatron is set forth in Equation
(1) as follows: ##EQU1## where m and n are the numbers of carbon
and hydrogen atoms in a hydrocarbon molecule (e.g., m.apprxeq.8 and
n.apprxeq.15 for gasoline). As used herein, "hydrogen-rich gas"
refers to a gas containing hydrogen and carbon monoxide. In
situations where the partial oxidation reaction of the hydrocarbon
fuel is with air, "hydrogen-rich gas" can also include N.sub.2.
Production of NO.sub.x in the plasma fuel converter is extremely
low because of the highly reducing atmosphere.
As stated above, it is desirable to develop special plasma fuel
converters capable of rapid response such that the potential
advantages for practical implementation in vehicles can be fully
realized. Rapid response plasma fuel converters are needed to
instantaneously provide hydrogen-rich gas, reduce engine pollutants
during start-up and to allow for use of hydrogen-rich gas during
load changes. As used herein, "rapid response" refers to plasma
fuel converters capable of responding and generating hydrogen-rich
gas on the order of a second or less. The present invention also
provides rapid response plasma fuel converters that are capable of
either steady state or pulsed modes of operation for the plasma
fuel converters.
Referring now to FIG. 1, a system 10 for fuel and air control for a
rapid response plasma fuel converter in accordance with the present
invention is shown. The plasma fuel converter could be an AC or arc
DC plasmatron or a high frequency plasmatron using inductive or
microwave heating. The plasma fuel converter could be operated in
either a continuous or pulsed mode of operation. System 10 includes
plasmatron 20, engine 40, and H.sub.2 /hydrocarbon fuel mixer 30
which can provide variable mixtures 64 of hydrogen-rich gas and
hydrocarbon fuel. System 10 also includes fuel pump and injector 60
and master automatic control units 52a and 52b which maintain the
desired mixture of air and fuel in the plasma fuel converter and in
the engine. Air sources 58 and 68 and hydrocarbon sources 54 and 62
are provided to system 10 as shown in FIG. 1.
In order for the plasmatron to rapidly respond, liquid fuels must
be introduced into the plasma fuel converter rapidly and in a
highly controlled manner. This can be accomplished utilizing fuel
pump and fuel injector 60 as shown in FIG. 1. Air 66 and 68 can be
introduced into system 10 using a compressor (not shown in FIG. 1).
The rate of air introduction is determined by the engine power
requirement. A portion of air flow 68 is fed to plasmatron as air
flow 58. The air flow 58 is determined by the accelerator pedal
controlled by the driver 50. The amount of fuel 54 introduced by
the fuel injector 60 is controlled by the air flow 58 using master
control 52a. The ratio of fuel to air introduced into plasmatron 20
is preferably designed to be very rich, i.e. it will be close to
the stoichiometric ratio in Equation (1). Hydrogen-rich gas 56
containing hydrogen, carbon monoxide and nitrogen are thus produced
in plasmatron 20.
For high engine loads, it may be desirable to provide hydrogen-rich
gas to engine 40 by a small storage tank (not shown in FIG. 1) in
addition to providing the gas directly from the plasma fuel
converter. In some situations, where the highest engine power
levels are required, it may be desirable to utilize 100% gasoline
operation (fuel 62) with stoichiometric fuel to air mixtures for
brief periods of acceleration; this mode of operation increases
cylinder volumetric power efficiency and reduces plasma fuel
converter electrical power requirements for a given amount of
engine power. This mode of operation would likely be used only for
conditions of highest power level. As further shown in FIG. 1,
hydrogen-rich gas flow 56 can be combined with hydrocarbon fuel
source 62 in different ratios by using mixer 30. Plow 64 of
hydrogen-rich gas, hydrocarbon fuel or combinations thereof is
controlled by master control 52b, which is determined by air flow
66 and engine load requirements. The driver could manually change
the ratio between the hydrogen-rich gas and gasoline depending on
driving conditions.
FIG. 2 illustrates a rapid power control circuit 80 for a
continuous arc plasmatron according to the present invention. The
power for processing the fuel in the plasma fuel converter must be
capable of being rapidly varied according to the flow rate to meet
engine load requirements. In a continuous arc plasmatron, the power
is changed by optimal variation of both arc plasma voltage and
current. The circuit shown in FIG. 2 allows for the control of
current and voltage.
The arc plasma in plasmatron 20 is operated with DC current in
order to facilitate stable operation and allow for substantial
variation in arc length and voltage. If current is maintained at a
constant level and gas flowrate is increased, the arc resistivity
and voltage increases, thereby adding power without increasing
current and consequently reducing electrode erosion. AC current is
used in the first part of the circuit to allow for rapid adjustment
of current. The diode circuit in FIG. 2 changes the current from AC
to DC for operation of the arc plasma.
As the demand for more power occurs, both voltage and current will
increase. The voltage and current control is used to provide the
required amount of power. Current control is achieved by the use of
saturable toroidal reactors 88, which is possible with AC current
input to the diode rectifier.
The controlled DC power for the plasmatron may also be obtained by
a controlled rectifier system in place of the saturable
reactor-diode rectifier system.
Circuit 80 also includes a high voltage ignitor circuit 84 to start
the arc plasma discharge. The circuit utilizes a capacitor 98 and
inductor 100 to provide a voltage of about 20 kilovolts to ignite a
DC arc in the plasmatron.
The voltage/current ratio may be varied for performance
optimization. This can be accomplished with voltage regulator 92,
current regulator 94, both of which are connected to battery 96 and
master control 52. As discussed herein, alternator 90, which is
also connected to master control 52, provides three phase AC
current to the transformer and charges battery 96.
In certain situations, it may be desirable to utilize rapid power
control in conjunction with pulsed plasmatron generation of
hydrogen-rich gas. Pulsed plasmatron operation would be optimized
for the required power gas flow by changing the repetition rate of
pulses at the same power per pulse of the plasmatron.
The pulsed plasmatron-internal combustion engine system could
operate with a unique circuit to allow variation of repetition rate
in accordance with engine power demand. This circuit is designed to
be compatible with a vehicular electrical system. An exemplary
pulsed plasmatron-engine electrical system suitable for use in the
present invention is illustrated in FIG. 3.
System 110 includes engine 40 that produces mechanical energy 112
to power generator 90. The generator 90 delivers three phase AC
current to transformer 118 and charges battery 96 by electrical
energy through circuits 114 and 116. Transformer 118 increases the
AC voltage which is supplied to the rectifier 86. Rectifier 86 in
turn supplies DC power 122 to the arc of the pulsed plasmatron 20.
As mentioned above, the generator 90 also is capable of providing
electrical energy 126 to charge the battery 96 using rectifier 124.
The battery 96 can be used to supply energy 128 to the spark
ignition system 132 and for the pulse network (PN) 130 for initial
startup of the plasmatron 20.
During engine operation, DC power will be always connected to the
pulsed plasmatron 20. As further shown in FIG. 3, the high voltage
and high frequency spark ignition system 132 delivers power 136 to
controller 138 to ignite discharge 140 in the plasmatron 20.
Controller 138 simultaneously will open the solenoid valve in the
fast acting valve (FAV) 144 via 142 to send a portion of the air 58
and fuel 54 to plasmatron 20 via 148. Air 58 and fuel 54 are fed to
plasmatron 20 as a mixture 146 that is controlled by master control
52a. The fuel injection system already existing in the vehicle
could be used as a FAV. As discussed above in connection with FIG.
1, the rate of air introduction 58 is determined by the engine
power requirement and the amount of fuel 54 is determined by the
air flow 58. The engine power requirement for air flow 58 is
determined by the accelerator pedal controlled by the driver in the
vehicle 50 and master control 52a is connected to the accelerator
pedal. The width of the pulse of such a system is about 1.5-10 ms.
The plasmatron will produce a pulse of plasma gas 56 which will be
delivered to the engine 40. Alternatively, hydrogen-rich gas can be
introduced into a storage tank for later use in the engine. In
either embodiment, hydrogen-rich gas 56 can be combined with other
fuel (such as hydrocarbon fuel 62 shown in FIG. 1).
During initial start-up, the plasmatron will be started utilizing
electrical energy 128 from the battery 96 supplied to the PN 130
and ignition system 132. The PN is a combination of several stages
of capacitors and inductors.
Several types of pulsed plasma fuel converters and systems
arrangements for use in accordance with the present invention will
now be discussed. These plasma fuel converters and system
arrangements are exemplary and are not to be construed as limiting.
Three types of plasma fuel converters that do not require water
cooling are illustrated in FIGS. 4-6. The plasma fuel converters
will provide uniform discharge with high average power. The
advantages of the uniform pulsed plasma fuel converters include
high plasma fuel converter thermal efficiency (no water cooling)
and long lifetime because of shorter contact time of the electrodes
with the plasma arc roots. The plasma fuel converters shown in
FIGS. 4-5 have been developed previously for other applications.
See, Hall et al., Initial Studies of a New Type of Ignitor: The
Railplug, SAE Paper 912319 (1991); Czernichowski et al.,
Multi-Electrodes High Pressure Gliding Discharge Reactor and Its
Applications for Some Waste Gas and Vapor Incineration, Proceedings
of Workshop on Plasma Destruction of Wastes, France (1990).
However, these plasma fuel converters have not been used for
hydrogen-rich gas generation in a vehicle. Nor have such plasma
fuel converters been utilized in systems capable of rapid response.
Each of these types of plasma fuel converters must accordingly be
modified for use in the present invention.
In a rail-gun type of a plasma fuel converter 150 as shown in FIG.
4, a cathode 152 is electrically insulated from the anode 154 by
insulator 156. A mixture of hydrocarbon fuel and air 160 is
introduced into plasma fuel converter 150 as further illustrated in
FIG. 4. Alternatively, hydrocarbon fuel and air can be introduced
separately and combined in the plasma fuel converter. The plasma
arc 158 sweeps axially between the two parallel electrodes 152 and
154 and reformed hydrogen-rich gas 162 exits the plasma fuel
converter. The acceleration is mainly provided by the interaction
of the arc current with the self-magnetic field and by gas flow.
The rail-gun plasma fuel converter will be modified to operate at
an order of magnitude larger size than previous designs (Hall et
al., Initial Studies of a New Type of Ignitor: The Railplug, SAE
Paper 912319 (1991)) and to provide conversion of hydrocarbon fuel.
The rail-gun plasma fuel converter further will be modified from
the previous designs by using pulsed fuel and air injection
coordinated with pulsed power as discussed previously in connection
with FIGS. 1-3 such that the plasma fuel converter is capable of
rapidly responding to engine load requirements and instantaneously
providing hydrogen-rich gas.
Referring now to FIG. 5, a gliding discharge plasma fuel converter
is shown. Plasma fuel converter 170 includes cathode 172
electrically insulated from anode 174 by insulator 176. A mixture
of hydrocarbon fuel and air 180 is introduced into plasma fuel
converter 170. In an alternative embodiment, hydrocarbon fuel and
air can be introduced separately and combined in the plasma fuel
converter. The arc discharges 178 are initiated at the spot where
the distance between the diverging electrodes is the shortest
(e.g., 178a) and progressively spread along the electrodes in the
direction of the reagent's flow until they disappear by themselves
after a certain path (Czernichowski et al., Multi-Electrodes High
Pressure Gliding Discharge Reactor and Its Applications for Some
Waste Gas and Vapor Incineration, Proceedings of Workshop on Plasma
Destruction of Wastes, France (1990)). This path is defmed by the
geometry of the electrodes, by the conditions of flow, and by the
characteristics of the power supplies. The gliding discharge plasma
fuel converter will be modified from the previous designs by using
pulsed fuel and air injection coordinated with pulsed power as
discussed previously in connection with FIGS. 1-3 such that the
plasma fuel converter is capable of rapidly responding to engine
load requirements and instantaneously providing hydrogen-rich
gas.
The radial gliding pulsed plasmatron shown in FIG. 6 is a
modification of a gliding discharge plasmatron such as that shown
in FIG. 5. Plasmatron 190 includes a plurality of cathodes 192
electrically insulated from anode 194 by insulator 196. Mixtures of
hydrocarbon fuel and air 202, 204 are introduced into plasmatron
190 as shown in FIG. 6. Discharges 198 will be simultaneously
ignited between the anode 194 and several radial cathodes 192 at
the shortest distance and will glide toward the center in the
direction of arrows 206 under the influence of the gas flow,
thereby producing hydrogen-rich gas 208. As a result, the lifetime
of the electrodes would be very high and the material would not be
limited to thermoconductive copper.
The rate of conversion of the hydrocarbon fuel would be higher
because of the increased residence time. The radial gliding
discharge plasmatron will be modified from the previous designs by
using pulsed fuel and air injection coordinated with pulsed power
as discussed previously in connection with FIGS. 1-3 such that the
plasmatron is capable of rapidly responding to engine load
requirements and instantaneously providing hydrogen-rich gas.
In another embodiment of the invention, the pulsed plasmatron for
hydrogen-rich gas production could be integrated with the cylinders
of an engine. In this way, the energy released by the partial
oxidation can be used in the engine. An exemplary pulsed gliding
discharge option for an integrated plasmatron hydrogen-rich gas
production-engine system is illustrated in FIG. 7. System 210
includes plasmatron 212 connected to engine 214. The operation of
the integrated system is similar to a plasma-jet ignition engine. A
main carburetor and intake manifold 232 controls the quantities of
hydrocarbon fuel 228 and air 230 such that the desired hydrocarbon
fuel-air mixture 234 fed to the combustion chamber 242 of engine
214 is properly proportioned. A separate carburetor and intake
manifold 220 feeds a fuel-rich mixture of fuel and air 224 into
plasmatron 212 using a fast acting valve (FAV) 222. Carburetor 220
controls the quantities of hydrocarbon fuel 216 and air 218 such
that hydrocarbon fuel-air mixture 224 introduced into plasmatron
212 via fast action valve 222 is properly proportioned.
After the lean mixture 234 is compressed in combustion chamber 242,
the solenoid controlled FAV 222 sends a portion of the rich
fuel-air mixture 224 into the plasmatron 212. Plasmatron 212
produces and injects a jet of hydrogen-rich gases 226 into the
combustion chamber 242, igniting the lean charge of mixture 234.
The combustion process produces mechanical energy 236 by the piston
238 reciprocating in engine cylinder 240. For this configuration,
the pulsed plasmatron must operate at gas densities that are
significantly higher than atmospheric density. The studies of the
railplug ignitor (Hall et al, Initial Studies of a New Type of
Ignitor: The Railplug, SAE Paper 912319 (1991)) have shown that
railplugs can produce a high velocity jet at a pressure of 200
psig.
In yet another embodiment of the invention, a pulsed plasmatron for
hydrogen-rich gas production could be incorporated into the
cylinder of an engine to provide a self-sustaining system such as
that shown in FIG. 8. This one cylinder engine would be operated
with a very rich mixture of hydrocarbon fuel and air and
consequently would produce very little NO.sub.x. During the partial
oxidation reaction, about 17 percent of the low heating value of
gasoline is released to the hydrogen-rich gas. In some situations,
it is desirable to transform at least part of this heat energy to
the mechanical energy of the piston motion and subsequently to the
electrical energy supplied to the plasmatron. Another part of heat
energy could be recovered by air incoming to the plasmatron. The
air will take energy during regenerative cooling of the cylinder
walls and then in the hydrogen-rich gas exhaust heat exchanger. In
this manner, the energy of the partial oxidation reaction can be
utilized in the system.
The system 250 illustrated in FIG. 8 includes plasmatron 252 and
engine 254. Engine 254 includes cylinder wall 258 and piston 256. A
generator 276 is connected to the shaft of piston 256.
Hydrocarbon fuel 272 is mixed with air 270 and is introduced into
plasmatron 252. Alternatively, hydrocarbon fuel and air can be
introduced into the plasmatron separately and combined within the
plasmatron. The plasmatron illustrated in FIG. 8 is a gliding
discharge plasmatron and thus arc discharges 280 are initiated at
the location where the distance between the diverging electrode is
the shortest. It will be appreciated by those skilled in the art
that other plasmatrons can be utilized in the system shown in FIG.
8 and that such modifications are within the scope of the present
invention. Hydrogen-rich gas 274 exits plasmatron 252 and is fed to
the combustion chamber 260 of engine 254. A portion of the heat
energy released reciprocates piston 256 in the directions of arrow
262. Mechanical energy produced by engine 254 powers generator 276,
thereby producing electricity 278. At least a portion of
electricity 278 can be utilized to power plasmatron 252, thereby
producing a self-sustaining system.
Another part of heat energy could be recovered by air 270 incoming
to the plasmatron 252. Air 264 will take energy during regenerative
cooling of the cylinder walls 258 of the engine 254 and then as air
266 in the hydrogen-rich gas 274 exhaust heat exchanger 268. In
order to prevent the leaking of hydrogen-rich gas to the
atmosphere, the entire plasmatron-engine unit could be enclosed in
a completely sealed shield (not shown in FIG. 8). Such a shield
could be formed of ceramic or the like. As discussed herein, a
portion of the incoming air could be injected through the seal in
order to create positive pressure and prevent leaking. It will be
appreciated by those skilled in the art that the system illustrated
in FIG. 8 can readily be modified for other alternatives within the
scope of the invention. For example and while not intending to be
limiting, one variation can include the use of two or more cylinder
units employed together.
In still another embodiment of the invention, it may be
advantageous to use a conventional catalytic or thermal reformer in
conjunction with the plasma fuel converter. The use of a catalytic
reformer could further increase fuel efficiency. Houseman et al.,
Hydrogen Engines Based on Liquid Fuels: A Review, Proceedings Third
World Hydrogen Energy Conference, p. 949 (1980). The plasma fuel
converter could be used to provide immediate production of
hydrogen-rich gas and to warm up the conventional reformer. The
conventional reformer could then be employed to produce
hydrogen-rich gas with greater efficiency than the plasma fuel
converter since it does not require external power. The plasma
reformer could then operate in parallel with the catalytic reformer
to provide fast response and extra levels of hydrogen-rich gas for
the engine.
In parallel operation, the conventional reformer preferably would
be sized so that it only needs to provide hydrogen-rich gas at
moderate flow level (e.g., on the order of twice the idle level).
Because conventional reformer size and cost are significant
factors, the resulting reduction of the conventional reformer size
by a factor of five or more could be significant. Additionally,
because operation of the conventional reformer is less of a power
drain than the plasma device, it would be utilized where
possible.
The plasma fuel converter and conventional reformer arrangement
could also be employed and used in series; e.g., the conventional
reformer could be warmed by hot gas and radiation from the plasma
fuel converter and could provide additional processing of the gas
from the plasma device.
FIG. 9 schematically shows an illustrative configuration for a
hybrid plasma fuel converter-conventional reformer device. System
290 includes plasma fuel converter 292, engine 294 and catalytic
reformer 296. Master control 302 and flow control valve 304 control
the quantity of air 298 while master control 302 and flow control
valve 306 control the quantity of hydrocarbon fuel 300 introduced
into plasma fuel converter 292. Hydrogen-rich gas 308 exits plasma
fuel converter 292 and is fed to catalytic reformer 296 and/or
engine 294. Flow to a catalytic reformer 296 and engine 294 is
regulated by flow control valves 310 and 312, respectively.
Master control 318 and flow control valve 320 regulate the flow of
air 314 to catalytic reformer 296 while master control 318 and flow
control valve 322 regulate the flow of hydrocarbon fuel 316 to
catalytic reformer 296. Reformed gases 324 are fed to engine 294.
As further shown in FIG. 9, reformed gases 324 can be combined with
hydrogen-rich gases 308 prior to introduction in engine 294 in a
predetermined manner utilizing flow control valve 312. The flow of
gases 308 and/or 324 entering engine 294 is determined by the
quantity of air 328 required for engine requirements and is
controlled by master control 326.
During startup, hot hydrogen-rich gas and possibly radiation from
the plasma fuel converter would pass through the catalytic
reformer, thereby providing sufficient heat to a temperature where
the catalytic reformer can effectively reform fuel. After the
catalytic reformer is warmed up, the control system could switch
fuel and air to it and the plasma fuel converter and catalytic
converter system could run in series or in parallel.
As discussed in U.S. Pat. Nos. 5,425,332 and 5,437,250, the major
contributor to air pollution in the U.S. is the fossil-fuel powered
motor vehicle. In 1987, 66 percent of the carbon monoxide emission,
43 percent of NO.sub.x, emissions, and 20 percent of particle
emissions came from motor vehicles alone. The rapid response and
pulsed operation capabilities of the plasma fuel converter and
systems provided by the present invention could significantly aid
in the improvement of air quality.
It should be appreciated by those skilled in the art that the
specific embodiments disclosed above may readily be utilized as a
basis for modifying or designing other methods or structures for
carrying out the same purpose of the present invention. It should
also be realized by those skilled in the art that such equivalent
constructions do not depart from the spirit and scope of the
invention as set forth in the appended claims.
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